Supervised alarm system



July 21, 1953 F. B. ALLEN suPERvIsED ALARM SYSTEM Filed Jung 17, 195

IN V EN TOR. FQANK B. A1. 4 e/v A Tron/EX Patented July 21, 1953 ySUPERVISED ALARM SYSTEM Frank B. Allen, Towaco, N. J., assignor to C-O-Two Fire Equipment Company, Newark, N. J., a corporation of DelawareApplication June 17, 1950, Serial No. 168,706

4 Claims. l

This invention relates to supervised alarm systems and more particularlyto a system for use with a detector such as the ionization type whereinthereis no current ilow through the detector until a predeterminedcondition has occurred.

A system of the type to be described may be used for re o1' smokedetection and may utilize an ionization detector. In the ionizationdetector a reference chamber and a test chamber have spaced electrodesupon which a predetermined potential diference is maintained, the air inboth of the chambers being ionized by the presence of a radioactivematerial, the apparatus being constructed so that upon the entry intothe test chamber of a uid such as. smoke the balanced condition isaffected and an electronic relay is actuated to provide an alarm.

In the event the detector is used to indicate fire or smoke, it isimportant that supervisory means be continuously operable to ascertainany failure in the system such as a broken wire or the removal of adetecting unit. As a detector of this sort draws practically no currentuntil an unbalance has occurred resulting from the disturbance of theionization condition in the test chamber, there is no current flow andthus it is difficult to supervise the condition of the circuit.

The present invention aims to provide a supervised alarm circuit for usewith a detector normally drawing practically no current.

Another object of the invention is to provide a supervised alarm circuithaving means to indicate the failure of the source of electrical energy.

It is also an object of the invention to provide y means to indicate ashort circuit occurring in the detector circuit.

Another object of the invention is to provide means to indicate theremoval of a detector unit from its mounting base.

A still further object of the invention is to provide a supervised alarmsystem which is simple and economical in manufacture and eicient inoperation.

A circuit in accordance with the invention is advantageous as it permitsthe use of an adaptor and testing means for the adjustment of thedetector in the position in which it is to be used.

Other objects and advantages of the invention will be apparent from thefollowing description and from the accompanying drawing which shows, byway of example, an embodiment of the invention.

In the drawings:

Figure 1 is a diagrammatical representation of 2 1 a supervised alarmsystem constructed in accordance with the invention.

Figure 2 is a diagrammatical representation of an individual detectorcircuit used in the system shown in Figure 1.

Referring to the drawings, there is shown' a supervised alarm system inaccordance with the invention connected to a source of alternatingcurrent supply I through atransformer Il. The alternating lcurrentsupplied by the transformer II is converted to direct current by therectifier I2 and ltered in the circuit I4 after which it isY passedthrough a relay coil I5 connected in series with a plurality of detectorunitsl and thence to ground. As shown in the drawing, the detector unitsIB are connected together for usein a single zone and a plurality ofparallel connections may be made to other detectors likewise connectedin one or more other zones.

The transformer II is preferably of the regulator type producing aconstant output voltage irrespective of minor variations in its inputvoltage. A primary winding I'I of the transformer II is connectedthrough a switch I9 and a fuse to the source of alternating currentsupply I0. A secondary heater winding 2l is connected to a heaterfilament 22 of the full-wave rectifier tube I2. A secondary load winding24 of the transformer II has its midpoint 25 grounded and its outsideleads 26 and 2 connected to anodes 29; and 3D of the full-wave rectifierI2. A cathode 3| of the full-wave rectier tube I2 is connected in seriesby a wire 32 to the lter I4 including an inductance 34 across the endsof which are connected a pair of grounding condensers 35. The output ofthe lter I4 is connected by a wire 35 in series with the coil I5 of asupervisory and alarm relay 31 having a pair of double-throw contactsand 48a. The outgoing lead of the relay coil I5 is connected by a wire4I from which the detector units I6 are connected in parallel by wires42. The detector units I6 are supported by mounting brackets 44 eachmade with 44. The detector unit I6 includes a control ionization chamberand a test ionization chamber 56, chamber 55 being vented to theatmosphere through a small aperture I in its wall for equalization ofthe control chamber pressure and the atmosphere pressure, while chamber56 has a comparatively large opening 59 for the easy movement of air tobe tested through the charnber. The control ionization chamber 55 hasits outer wall 69 forming an electrode connected by a wire 6I toterminal 52 of the base 54. An intermediate insulated portion 64 carriesa partition 65 having thereon a small portion of radioactive material 66which provides for the ionization of the air in the control chamber 55and in the test chamber 56. The test chamber 56 has its outer wallforming an electrode 61 connected by a wire 69 to terminal 5I of itsbase. Within the chambers 55 and 56 are positioned electrodes I0 and '|Iboth spaced from the walls of their respective chambers and insulatedtherefrom and connected by a wire 'l2 to the control electrode 'I3 of acold cathode tube '14. Plate 'I5 of the cold cathode tube 'I4 isconnected to the wire 6I and a second plate 'I6 is connected to the wire69 thereby connecting the cold cathode tube in parallel across the twochambers 55 and 56. The ionization chambers and the cold cathode tubeare mounted in a suitable casing on the base 54 to provide a detectorassembly easily removable or replaceable, if desired.

In the event a single detector unit I6 is to be used in a zone, itsterminal 41 is grounded, while if a plurality of units are to be used ina zone, a ground wire TI is connected to the terminal 46 of the lastdetector providing a series ground connection through all of thedetector units in one zone. The mounting brackets have their terminalsand 4l' connected by jumpers 'I9 while the detector bases 54 have theirterminals 49 and connected by jumpers 86. A series connection betweeneach detector is provided by connecting terminal 46 of the rst detectorunit by a wire 8| with terminal 41 of the next unit and making likeconnections between each of the detector units I6. By this means aseries connection is made through each detector unit I6 to ground sothat the removal of one of the detector units will indicate an opencircuit and produce a trouble signal.

The movable contact 40 of the supervisory and alarm relay 31 is used tocomplete a circuit to provide an indication of a zone in which re orother conditions is present. Movable contact 40 is connected by a wire84 to one side of the supply transformer coil I`| while xed Contact 39is connected by a wire 86 to a zone indicator 9T having its otherterminal connected by wire 89 to the other side of the coil I'I of thesupply transformer. The other fixed contact 38 is connected in parallelwith the fixed contact 39.

The double-throw contact 49a is connected to one side of the source ofsupply through the wire 84. Fixed contact 9| is connected through a wire92 to one side of the coil 94 of an alarm relay 95, the other side ofthe coil 94 is connected to the other side of the source of supply by awire 96. Fixed contact 91 of the double-throw contacts 40a is connectedby a wire 99 to one side of a trouble buzzer |09. The other side of thetrouble buzzer is connected by the wire 89 to one side of the coil II ofthe power supply. The alarm relay 95 has additional contacts IDI and |02which may be connected in a circuit with alarm gongs to a centralstation, or to initiate the discharge of a fire extinguishing system.

The supervisory and alarm relay 37 preferably has a wound armature sothat its contacts may be positioned depending upon the current flowthrough the relay coil I5. Under conditions of no current or under apredetermined minimum current flow, the armature moves to connectcontact 40a with 91 to give a trouble alarm, and contacts 49 and 39 areconnected to give a zone indication. For a greater current flow throughthe relay coil I5, the armature changes the position of the movablecontacts to a floating position between the fixed contacts. Underconditions of a still greater current, the armature causes the movablecontacts to move upwardly to connect contacts 39 and 49 for the zoneindicator 81 and to connect contacts 40 and 9| to the fire alarm relay95. In order to produce suicient current flow to maintain the movablecontacts iloating during normal operation of the system, a resistor |04is connected between the wire 4| and the terminal 45 of the detectormounting base by a wire I 65. A circuit is then provided drawing apredetermined minimum current through the relay coil I5 so as to holdthe contacts away from the trouble position.

In operating a system in accordance with the invention, it is connectedto a source of alternating supply ID thereby energizing the transformerI I and high voltage is applied to the plates ol the rectifying tube I2.The output of the rectiying tube I2 passes through the iilter |4,through the coil I5 of the supervisory relay S1, through the resistor|94, the jumper connection 'I9 of the mounting block, through the jumperconnection 89 of the detector base, and through wires 8|, and to groundthrough connection 11.

In the event any of the detectors i5 are removed from their mountingbracket 44, the circuit for the resistor |84 is opened thereby causingthe supervisory relay to cause the trouble alarm to be given. Likewise,if an open circuit occurs in the wiring to the detector unit I6, thecurrent through the relay coil I5 drops to zero causing the troublealarm to be sounded and causing a zone indication. A failure of thealternating current supply likewise causes the relay to drop to thetrouble position.

In the event a condition is present, such as nre, causing an unbalanceof the ionization chambers 55 and 56, the cold cathode tube 'i4 istriggered to break down and cause an increased current ow through therelay coil l5 thereby producing a iire alarm and zone indication.Further, in the event a short circuit occurs in the detector or zonewiring an alarm signal is given.

In order to adjust or set the detector I6 for any predeterminedcondition, an adaptor jack (not shown) may be interposed between thedetector base 54 and the mounting bracket di@ thereby providing forconnections to adjust the detector while it is positioned in the spacewherein it is to be used.

It conditions warrant the installation of one or more additional zones,connections thereto may be made in parallel to wires E4, 92, 69 and 86as indicated at |98, and an additional zone indicator |06 may beconnected by a wire I i.

From the foregoing description it may be seen that a supervised alarmsystem has been provided for use with a detector normally drawingpractically no current. Supervision is given of the `failuze of thepower supply, the presence of a short circuit, the presence of re and anindication of the removal of one of the detector units.

While the invention has been illustrated and described with reference toa specific embodiment thereof, it will be understood that otherembodiments may be resorted to without departing from the invention.Therefore, the form of the invention set out above should be consideredas illustrative and not as limiting the scope of the liollowing claims.

l claim:

1. An electrically actuated alarm system comprising an alarm signal toindicate a predetermined condition, a trouble signal to indicatemalfunctioning of the system, single relay means to close a circuit tothe trouble signal for a current now below a minimum amount and to openthe trouble circuit for a current flow above the minimum amount and toclose a circuit to the alarm signal for a current lorw of the samepolarity above a predetermined amount, a resistor in series with therelay means to provide a current ow above the minimum amount to open thetrouble signal circuit, a detector connected in parallel with theresistor and responsive to a predetermined condition to provide acurrent flow above the predetermined amount to close the alarm circuit,a mounting bracket for the detector carrying a pair of contactsconnected in series, a base for the detector, and a second pair ofcontacts connected in series and carried by the base, whereby when thedetector is in position on the mounting block the two `pairs of contactsare in series.

2. An electrically actuated alarm system comprising an alarm signal toindicate an ionization condition, a trouble signal to indicatemalfunctioning of the system, a relay switch having a set ofdouble-throw contacts, one set of contacts connected to the alarm signaland the other set connected to the trouble signal, a single relay coilto actuate the relay switch, the relay switch constructed and arrangedto close the trouble contacts for a current flow through the relay coilbelow a minimum amount and to open the trouble contacts for a currentflow of the same poiarity above the minimum amount and to close thealarm contacts for a current flow above a predetermined amount, aresistor in series with the relay coil to provide a current flow abovethe minimum amount to open the trouble signal circuit, a detectorconnected in parallel with the resistor responsive to an ionizationcondition to pass current to provide a current flow above thepredetermined amount to close the alarm circuit, a mounting bracket forthe detector, a pair of contacts on the mounting bracket in series withthe relay coil, a base for the detector, and a pair of series-connectedcontacts on the base, the base series contacts adapted to coact with thebracket contacts to complete the relay circuit to the resistor and thedetector whereby a trouble its bracket.

3. An electrically actuated alarm system comprising alarm sign-al meansto indicate a predetermined condition, a trouble signal to indicatemalfunctioning of the system, a circuit adapted to be connected to asource of electric current, a resistor connected across the circuit todraw a predetermined current therethrough, a detector responsive to thepredetermined condition to provide additional current through thecircuit of the same polarity as the current through the resistor, rstswitch means, a set of double-throw contacts for the first switch means,one set of contacts connected to the alarm signal and the other setconnected to the trouble signal, second switch means, a set ofdouble-throw contacts for the second switch means, a zone indicator,both of said second sets of double contacts connected` to the zoneindicator, and single relay means responsive to the current in thecircuit to close the trouble switch for a current flow below apredetermined minimum amount and to close the alarm switch upon the flowof a predetermined additional amount of current and to close one set ofthe zone indicator switch contacts with the alarm contacts and the otherset of zone contacts with the trouble contacts so that the location ofthe condition or trouble is given.

4. An electrically actuated alarm system comprising alarm signal meansto indicate a predetermined condition, trouble signal means to indicatemalfunctioning of the system, electric circuit connection means, relaymeans to operate the signals, la resistor connected in the circuit inseries with the relay to draw a predetermined current therethrough fornormally preventing actuation of the trouble signal means, a detectorresponsive to the predetermined condition to provide additional currentthrough the relay of the same polarity as the current through theresistor for the actuation of the alarm signal, a mounting bracket forthe detector, a pair of contacts carried by the mounting bracket andconnected in series with the resistor, a base for the detector, and apair of contacts connected in series and carried by the base, the basecontacts cooperating With the bracket contacts to complete the circuitthrough the resistor, whereby upon the removal of the detector and itsbase the trouble signal is actuated.

FRANK B. ALLEN.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date.

1,229,939 Goldstein June 12, 1917 1,909,212 Muehter May 16, 19332,000,074 Grant, Jr. May 7, 1935 2,473,940 Clark June 21, 1949

